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Re: Pizza Example

From: Laconic2 <laconic2_at_comcast.net>
Date: Fri, 23 Apr 2004 14:41:27 -0400
Message-ID: <T9KdnfV0iKK4_hTdRVn-uw@comcast.com>


"Eric Kaun" <ekaun_at_yahoo.com> wrote in message news:4Zcic.11391$Jr5.8164_at_newssvr31.news.prodigy.com...
> Possibly, but we're not talking about individual problem solving, at least
> not all the time. We're talking about information structures for a
business.
> And if you have multiple data models, you're going to have mapping
problems,
> probably severe ones. At some point the business has to (or should!)
define
> what it means by its data, and it's better to do that in one way, unless
you
> can very carefully identify non-overlapping domains which have a need for
> different paradigms. I've never seen such a thing, but that doesn't mean
the
> black swan doesn't exist.

The ER model was such a thing when I first started working with databases. Most of the existing databases were built on the Network (CODASYL) model, and many of the new databases were to be built on the relational model. It turns out that, if you have a good ER model of the data requirements, this "common model" can be turned into either a CODASYL model or a Relational model, as you choose.

So ER was "neutral" with regard to the question of whether a CODASYL DBMS or a Relational DBMS was the right tool to implement with. CODASYL databsaes for which there was an ER model were easy to convert to relational. The ones without and ER model were much harder.

It's for that reason that I like the idea of using the ER model as the basis for an enterprise wide data model. It could even span things that are not databases, like forms and reports. Received on Fri Apr 23 2004 - 13:41:27 CDT

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